The invention relates to a circuit arrangement for the recording of data on a magnetic recording carrier wherein synchronized high frequency bias is superimposed on the data signal to be recorded.
In the case of a recording of data on a magnetic recording carrier, for example a magnetic tape or a magnetic disk, it is already generally known to supply data signals representing the data to be recorded, to a write amplifier which generates a write current proportional to the data signals and supplies the latter write current to a magnetic head. For the allocation of the data to the data signals, a plurality of recording modes, for example, the NRZI-recording mode, the MFM-recording mode, or the GCR-recording mode, are available.
From European published patent application No. 0030 644 it is already known, in the case of a recording of data on a magnetic recording carrier, to superimpose on the data signals high-frequency magnetic bias signals. The magnetic bias signals are synchronized with the data signals. Through the utilization of the magnetic bias signals, the amplitude of the data signals can be reduced so that, during the recording operation, crosstalk from recording magnetic heads to reading magnetic heads is reduced. Furthermore, through the magnetic bias signals the recording operation is linearized so that the changes in the data signals, which correspond to the changes of the magnetization on the recording carrier, can be more precisely recognized. This is achieved, in particular, through the synchronization of the magnetic bias signals and the data signals.
It would be conceivable to sum up the data signals and the magnetic bias signals corresponding to their amplitude and to supply the sum signal to a write amplifier. The write amplifier in this case would have to be designed in the form of an analog amplifier and would have to exhibt a comparatively high limit frequency. Furthermore, it would be conceivable to provide for the data signals and for the magnetic bias signals a respective separate write amplifier, designed as a differential amplifier or controlled current source. This would require a comparatively great outlay and also the danger exists that, as a consequence of the high frequency of the magnetic bias signals, phase displacements between the magnetic bias signals and the data signals would occur.